The `start` convention is a CRA convention but nobody else of the modern
frameworks / tools use this convention for a file watcher and dev mode.
Instead the common convention is `dev`. Instead `start` is for running a
production build that's already been built.
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Co-authored-by: Sebastian Silbermann <silbermann.sebastian@gmail.com>
It's confusing to new contributors, and me, that you're supposed to use
`yarn build-combined` for almost everything but not fixtures.
We should use only one build command for everything.
Updated fixtures to use the folder convention of build-combined.